Life Sciences Commons^™

Visibility, Visual Awareness, And Visual Masking Of Simple Unattended Targets Are Confined To Areas In The Occipital Cortex Beyond Human V1/V2, Peter U. Tse, Susanna Martinez-Conde, Alexander A. Schlegel, Stephen L. Macknik

Dartmouth Scholarship

In visual masking, visible targets are rendered invisible by modifying the context in which they are presented, but not by modifying the targets themselves. Here, we localize the neuronal correlates of visual awareness in the human brain by using visual masking illusions. We compare monoptic visual masking activation, which we find within all retinotopic visual areas, with dichoptic masking activation, which we find only in those retinotopic areas downstream of V2. Because monoptic and dichoptic masking are equivalent in magnitude perceptually, the present results establish a lower bound for maintenance of visual awareness of simple unattended targets. Moreover, we find …

The Role Of Cuticular Pheromones In Courtship Conditioning Of Drosophila Males, Kathleen King Siwicki, Paul Nicholas Riccio , '05, Lisa Ladewski , '02, F. Marcillac, L. Dartevelle, Stephanie Alexis Cross , '04, J.-F. Ferveur

Biology Faculty Works

Courtship conditioning is an associative learning paradigm in Drosophila melanogaster, wherein male courtship behavior is modified by experience with unreceptive, previously mated females. While the training experience with mated females involves multiple sensory and behavioral interactions, we hypothesized that female cuticular hydrocarbons function as a specific chemosensory conditioned stimulus in this learning paradigm. The effects of training with mated females were determined in courtship tests with either wild-type virgin females as courtship targets, or with target flies of different genotypes that express distinct Cuticular hydrocarbon (CH) profiles. Results of tests with female targets that lacked the normal CH profile, and …

Src-Dependent Tyrosine Phosphorylation At The Tips Of Growth Cone Filopodia Promotes Extension, Estuardo Robles, Stephanie Woo, Timothy M. Gomez

Neuroscience: Faculty Publications

Extracellular cues guide axon outgrowth by activating intracellular signaling cascades that control the growth cone cytoskeleton. However, the spatial and temporal coordination of signaling intermediates remains essentially unknown. Live imaging of tyrosine phosphorylation in growth cones revealed dynamic phospho-tyrosine (PY) signals in filopodia that directly correlate with filopodial behavior. Local PY signals are generated at distal tips of filopodia during extension and are lost during retraction. Active Src family kinases localize to the tips of filopodia, and Src activity regulates both filopodial dynamics and local PY signaling. Positive guidance cues stimulate filopodial motility by locally increasing tyrosine phosphorylation in a …

Extraocular Muscle Activity, Rapid Eye Movements And The Development Of Active And Quiet Sleep, Adele M. H. Seelke, Andrew J. Gall, Karl Æ. Karlsson, Mark S. Blumberg

Faculty Publications

Rapid eye movements (REMs), traditionally measured using the electrooculogram (EOG), help to characterize active sleep in adults. In early infancy, however, they are not clearly expressed. Here we measured extraocular muscle activity in infant rats at 3 days of age (P3), P8 and P14-15 in order to assess the ontogeny of REMs and their relationship with other forms of sleep-related phasic activity. We found that the causal relationship between extraocular muscle twitches and REMs strengthened during the first two postnatal weeks, reflecting increased control of the extraocular muscles over eye movements. As early as P3, however, phasic bursts of extraocular …

Donepezil Effects On Mood In Patients With Schizophrenia And Schizoaffective Disorder, S Craig Risch, Michael D. Horner, Susan R. Mcgurk, Simmy Palecko, John S. Markowitz, Ziad Nahas, C. Lindsay Devane

Dartmouth Scholarship

Donepezil, 5 mg/d for 6 wk then 10 mg/d for 6 wk, and placebo daily for 12 wk in a double-blind cross-over paradigm, was added to the therapeutic regimen of 13 patients with schizophrenia or schizoaffective disorders, clinically stable on atypical antipsychotic medications. Patients had varying degrees of depressive symptoms, ranging from no depression to clinically significant depression. There was no worsening or induction of depression in individual patients or the group as a whole. In addition there was a statistically significant antidepressant effect in the group as a whole during the donepezil condition and a clinically significant antidepressant effect …

Sheep Updates 2005 - Part 1, R. W. Kelly, R. Kingwell, A. R. Bray, Chris Oldham, Graeme Martin, D. Blanche, D. Ferguson, Keith Crocker, Di Evans

Sheep Updates

This session covers seven papers from different authors: Boosting lambing percentages of WA sheep flocks. R.W. Kelly CSIRO Livestock Industries, Floreat WA , R. Kingwell Department of Agriculture WA, Kiwis can fly - 30% higher lambing in 15 years, AR Bray, Meat and Wool New Zealand, Wellington, New Zealand Rams are not a trivial expense, so what can you do to maximise on your investment? Chri Oldham, Department of Agriculture Western Australia, Graeme Martin, University of West Australia. Care for mun - fetal programming, lamb survival and lifetime performance. RW Kelly CSIRO Livestock Industries, Floreat WA Boost lamb survival - …

The Neural Substrates Of Infant Sleep In Rats, Karl Æ. Karlsson, Andrew J. Gall, Ethan J. Mohns, Adele M. H. Seelke, Mark S. Blumberg

Faculty Publications

Sleep is a poorly understood behavior that predominates during infancy but is studied almost exclusively in adults. One perceived impediment to investigations of sleep early in ontogeny is the absence of state-dependent neocortical activity. Nonetheless, in infant rats, sleep is reliably characterized by the presence of tonic (i.e., muscle atonia) and phasic (i.e., myoclonic twitching) components; the neural circuitry underlying these components, however, is unknown. Recently, we described a medullary inhibitory area (MIA) in week-old rats that is necessary but not sufficient for the normal expression of atonia. Here we report that the infant MIA receives projections from areas containing …

Limits Of Learning Enhancements With Nicotine In Old Male Rats, George Taylor, Carl Bassi, Juergen Weiss

Psychology Faculty Works

Findings with young adult humans and animal models suggest that nicotine may serve both neuroprotective and cognition enhancing roles in old animals. A pair of experiments was conducted to examine drug-induced modification of the cholinergic nicotinic receptor subtype on rates of learning by young and aged rats. In experiment I males (4-7 months or 20-25 months old) were administered nicotine (0.0, 0.3 or 0.7 mg/kg injected s.c. daily) and tested in both a T-maze non-spatial discrimination paradigm and a hole board spatial task. Nicotine failed to improve acquisition by young animals on either task. Nicotine also failed to improve non-spatial …

The Retrograde Spread Of Synaptic Potentials And Recruitment Of Presynaptic Inputs, Brian L. Antonsen, Jens Herberholz, Donald H. Edwards

Neuroscience Institute Faculty Publications

Lateral excitation is a mechanism for amplifying coordinated input to postsynaptic neurons that has been described recently in several species. Here, we describe how a postsynaptic neuron, the lateral giant (LG) escape command neuron, enhances lateral excitation among its presynaptic mechanosensory afferents in the crayfish tailfan. A lateral excitatory network exists among electrically coupled tailfan primary afferents, mediated through central electrical synapses. EPSPs elicited inLGdendrites as a result of mechanosensory stimulation spread antidromically back through electrical junctions to unstimulated afferents, summate with EPSPs elicited through direct afferent-to-afferent connections, and contribute to recruitment of these afferents. Antidromic potentials are larger if …

Daily Rhythm Of Cerebral Blood Flow Velocity, Deirdre A. Conroy, Arthur J. Spielman, Rebecca Q. Scott

Publications and Research

Background: CBFV (cerebral blood flow velocity) is lower in the morning than in the afternoon and evening. Two hypotheses have been proposed to explain the time of day changes in CBFV: 1) CBFV changes are due to sleep-associated processes or 2) time of day changes in CBFV are due to an endogenous circadian rhythm independent of sleep. The aim of this study was to examine CBFV over 30 hours of sustained wakefulness to determine whether CBFV exhibits fluctuations associated with time of day.

Methods: Eleven subjects underwent a modified constant routine protocol. CBFV from the middle cerebral artery was monitored …

Sodium And Calcium Current-Mediated Pacemaker Neurons And Respiratory Rhythm Generation, Christopher A. Del Negro, Consuelo Morgado-Valle, John A. Hayes, Devin D. Mackay, Ryland W. Pace, Erin A. Crowder, Jack L. Feldman

Arts & Sciences Articles

The breathing motor pattern in mammals originates in brainstem networks. Whether pacemaker neurons play an obligatory role remains a key unanswered question. We performed whole-cell recordings in the pre-Botzinger complex in slice preparations from neonatal rodents and tested for pacemaker activity. We observed persistent Na⁺ current (I_NaP)-mediated bursting in ∼5% of inspiratory neurons in postnatal day 0 (P0)-P5 and in P8-P10 slices. I_NaP-mediated bursting was voltage dependent and blocked by 20 μm riluzole (RIL). We found Ca²⁺ current (I_Ca)-dependent bursting in 7.5% of inspiratory neurons in P8-P10 slices, but in …

The Temporal Context Model In Spatial Navigation And Relational Learning: Toward A Common Explanation Of Medial Temporal Lobe Function Across Domains, Marc W. Howard, Mrigankka S. Fotedar, Aditya V. Datey, Michael E. Hasselmo

Psychology - All Scholarship

The medial temporal lobe (MTL) has been studied extensively at all levels of analysis, yet its function remains unclear. Theory regarding the cognitive function of the MTL has centered along 3 themes. Different authors have emphasized the role of the MTL in episodic recall, spatial navigation, or relational memory. Starting with the temporal context model (M.W. Howard and M. J. Kahana, 2002), a distributed memory model that has been applied to benchmark data from episodic recall tasks, the authors propose that the entorhinal cortex supports a gradually changing representation of temporal context and the hippocampus proper enables retrieval of these …